What this scroll alludes to is a teaching in swordsmanship in which a true warrior is one that has attained an equanimous mind.
The rock in this sense is the mind, but don’t think of it as a stationary rock. The mind should be in a free flowing state like a rock rolling down a hill. Along the way, the rolling rock may touch or run into things, but it just calmly and effortlessly moves around the impediment. It could, theoretically, keep on rolling forever.
One of the goals in Aikido training is to develop an unaffectable mind which is always calm and free flowing. In swordsmanship, this is referred to as having an immovable mind or an non-abiding mind.
When a person engages us, if we react to their advances then we are mindless. If we have equanimity then we can be mindful and thus choose the appropriate course of action.
This kind of mindfulness is necessary in Aikido based on O’Sensei’s philosophy of non-violence. Furuya Sensei explained it:
Aikido has the effectiveness to throw the opponent but, we have decided that in order for it to be real Aikido, it must express a goodness, respect and nobility for life that does not allow us to use excessive violence or a “by any means necessary” attitude.
Being very aware of what we do, we become aware of the consequences and seek to achieve a higher level of existence in this world and within our lives to become good human begins, we are then practicing Aikido as a “do.”
The power thus comes from being a stone warrior who’s mindfully aware and who always acts with appropriate action. This what we strive for and this is one of the true secrets of Aikido training.